A commercially available motherboard of a computer system mainly consists of a central processing unit (CPU), a chipset and some peripheral circuitry. CPU is the core of the computer system in charge of the coordination among parts of the computer system and doing logic operations as well. The composition of a chipset can be various, and a chipset composed of a north bridge chip and a south bridge chip is the main stream in current market. The north bridge chip and the south bridge chip are assigned with different tasks. In principle, the north bridge (NB) chip takes charge of the high-speed-bus associated parts on the motherboard while the south bridge (SB) chip deals with low-speed bus communication in the system.
The north bridge chip communicates with the CPU via a front side bus (FSB), and in addition, the north bridge chip is coupled to an Accelerated Graphics Port (AGP) interface via an AGP bus and further coupled to a random access memory (RAM) via a memory bus. The south bridge chip is coupled to a peripheral component interconnect (PCI) interface via a PCI bus, and further coupled to other devices such as industry standard architecture (ISA) interface, integrated drive electronics interface, universal serial bus (USB) interface, keyboard and mouse. Chipset takes charge of communication of the CPU with the peripheral equipment, including access to RAM. Signals or commands to be read or executed in the computer system need be processed by CPU and temporarily stored in RAM via the north bridge chip of the chipset.
The north bridge chip comprises a CPU controller in communication with the CPU, a memory controller in communication with the RAM, an Accelerated Graphics Port (AGP) controller in communication with an AGP interface, and a SB controller in communication with the south bridge chip. The data are written, read or refreshed by accessing to the RAM entry by entry, so the data flow should be well ordered by the memory controller. Furthermore, the requests issued by various peripheral devices for access to the RAM are directed by a traffic controller disposed in the north bridge chip.
With the advance of processing performance of computer systems, the processing capacity, speed and frequency are getting higher and higher, and the kinds and amount of data that the computer system needs to process are getting more and more. When there are lots of data to be processed at the same time, the data transfer burden of the north bridge chip would be huge, and thus high heat of the north bridge chip and power consumption of the computer system are inevitable. Nevertheless, for supporting a majority of workload, high-speed and high-frequency processing specifications are still adopted. In other words, high-speed and high-frequency processing of the north bridge chip is still performed even if the data or signals to be processed by the north bridge chip decreases (for example when CPU throttling is enabled to reduce frequency). As such, unnecessary power consumption of the computer system and undesired high heat of the north bridge chip occur.